Systems and methods for spinal rod insertion and reduction

ABSTRACT

A guide assembly includes a spinal screw assembly having a bone screw and a spinal rod holder; and a spinal rod guide having first and second elongated arc portions defining a pair of longitudinal slots extending along the first and second arc portions, each of the first and second arc portions further defining at least one recess extending transversely from each of the longitudinal slots, the at least one recess configured to receive at least a portion of a reduction tool to enable reduction of a spinal rod received within the spinal rod holder.

BACKGROUND

The present invention relates to spine fixation components, constructsand assemblies and, more particularly, to a construct for theimplantation of a spinal rod.

Spinal orthopedic assemblies and constructs such as spine plates, spinalbone screw assemblies for spinal rods and other devices (spinalcomponents) have made a profound contribution to the correction ofspinal deformities, accidents and other problems in the thoracic, lumbarand sacral spine. These and other spinal devices are fixed to vertebraeusing vertebral bone screws. Vertebral bone screws are speciallydesigned and manufactured bone screws that are placed into the bone of avertebra. One typical placement of a bone screw for the fixation of aspinal component is through a pedicle of the vertebral body. Vertebralbone screws placed in this manner offer superior strength and pull-outresistance as compared to other forms of fixation in spine surgery. Theability to achieve pedicle fixation has allowed surgeons to obtain moresecure fixation of the involved vertebral segments, which permits morepowerful correction of spine problems and reported better clinicaloutcomes. Vertebral bone screws for pedicle fixation are typically knownas pedicle screws.

Of the various spinal components, spinal rods are used in certaincircumstances to fix a number of vertebrae in a particular orientation.As such, spinal rods must be fixed to the vertebrae. The pedicle screwprovides a solid foundation for the attachment of a spinal rod. In oneform, a spinal rod may be held relative to a pedicle screw by a spinalrod connector that is coupled to the pedicle screw. The spinal rodconnector is typically rotationally connected to the pedicle screw inorder to allow various connection orientations of the spinal rodrelative to the longitudinal axis of the pedicle screw. The spinal rodconnector includes features that allow the reception and capture of thespinal rod. This is accomplished by placing the spinal rod through anopening in the body via which the pedicle screw and spinal rod connectoris attached to the vertebra. The spinal rod is then placed through thebody opening and directed into and oriented on the spinal rod connector.Thereafter, the spinal rod must be secured to each individual spinal rodconnector. This is typically accomplished by installing a spinal rodconnector screw onto the spinal rod connector via a tube temporarilyconnected to the spinal rod connector. Because of this complicatedprocedure, it is fairly difficult and/or cumbersome to situate and mounta spinal rod onto a spinal rod connector of a vertebral bone screw.

In view of the above, it is clear that there is a need for a bettermanner of mounting a spinal rod onto a spinal rod connector of avertebral bone screw.

SUMMARY

The present invention relates to a spinal rod guide for mounting aspinal rod onto a spinal rod holder of a vertebral bone screw,particularly, but not necessarily, for use in minimally invasivesurgery. The spinal rod guide is configured to extend between an openingin a patient's body and the spinal rod holder of the vertebral bonescrew, to receive a spinal rod therein, and thereafter accurately guidethe spinal rod into the spinal rod holder. The spinal rod guide isdefined by a first elongated arc portion and a second elongated arcportion that together define a first elongated slot and a secondelongated slot sized for the introduction and placement of the spinalrod into the spinal rod holder.

The first and second elongated arc portions together define an elongatedtube that allows additional spinal rod components to be guided andplaced into/onto the spinal rod connector, particularly, but notnecessarily, for securing the spinal rod into the spinal rod holder.

An embodiment of the spinal rod guide comprises a first elongated arcportion that is attachable to a spine rod holder of a spinal rod bonescrew assembly and a second elongated arc portion that is attachable tothe spine rod holder of the spinal rod bone screw assembly. First andsecond longitudinal slots are defined between sides of the first andsecond arc portions and which extend from a top of the elongated arcportions to a bottom of the elongated arc portions. The two longitudinalslots are situated at diametrically opposite sides thereof. Eachlongitudinal slot aligns with a spinal rod slot of the spinal rod holderto thereby allow easy placement of the spinal rod into the spinal rodholder. Thereafter, the elongated arc portions provide directcommunication and alignment with the top of the spinal rod holder bydefining an elongated tube in order to receive a spinal rod holder drivescrew for securing the spinal rod into the spinal rod holder. In thisembodiment, the spinal rod guide is removed from the spinal rod holderafter installation and securing of the spinal rod.

The present invention also relates to a spinal rod guide assembly formounting a spinal rod into a spinal rod holder of a vertebral bone screwassembly of the spinal rod guide assembly particularly, but notnecessarily, for use in minimally invasive surgery. The spinal rod guideassembly includes a spinal rod guide that is initially attached to thespinal rod holder of the vertebral bone screw assembly. The spinal rodguide is configured to extend from an opening in a patient's body to thespinal rod connector, to receive a spinal rod therein, and thereafteraccurately guide the spinal rod into the spinal rod connector. Thespinal rod guide defines a guide tube for the introduction and placementof additional spinal rod components onto the spinal rod connector,particularly, but not necessarily, for securing the spinal rod into thespinal rod holder. The spinal rod guide is temporarily attached to thespinal rod connector in a manner that allows for easy detachment of thespinal rod guide from the spinal rod holder.

An embodiment of the spinal rod guide assembly includes a vertebral bonescrew, a spinal rod holder pivotally coupled to the vertebral bonescrew, and an elongated guide tube defined by first and second elongatedarc portions that are attached onto a top of the spinal rod holder. Theelongated guide tube has first and second longitudinal slots extendingfrom a top of the elongated guide tube to a bottom of the elongatedguide tube that align with first and second spinal rod slots of thespinal rod holder. The two longitudinal slots of the elongated guidetube and the two spinal slots of the spinal rod holder are situated atdiametrically opposite sides. The slots allow easy placement of thespinal rod into the spinal rod holder. The elongated tube moreoverprovides direct communication and alignment with the top of the spinalrod holder in order to receive a spinal rod connector drive screw forsecuring the spinal rod into the spinal rod holder. The spinal rod guideis scored or otherwise connected at a junction between the spinal rodguide and the spinal rod holder such that the spinal rod guide is easilybroken or snapped off from the spinal rod holder once installation ofthe spinal rod is complete.

Another embodiment relates to a guide assembly comprising a spinal screwassembly comprising a bone screw and a spinal rod holder; and a spinalrod guide comprising first and second elongated arc portions defining apair of longitudinal slots extending along the first and second arcportions, each of the first and second arc portions further defining atleast one recess extending transversely from each of the longitudinalslots, the at least one recess configured to receive at least a portionof a reduction tool to enable reduction of a spinal rod received withinthe spinal rod holder.

Another embodiment relates to a spinal rod installation kit comprising aguide assembly comprising a bone screw assembly and a pair of arcuateflanges extending from the screw assembly, the arcuate flanges definingat least one longitudinal slot therebetween; a spinal rod configured tobe guided toward a fully seated position by the arcuate flanges; aspacer having a first end and a second end, the second end configured toengage the spinal rod; and a reducer configured to engage the first endof the spacer and having an inner member moveably coupled to an outermember; wherein rotation of the outer member relative to the innermember causes a longitudinal movement of the screw assembly relative tothe spinal rod.

Another embodiment relates to a method of reducing a spinal rod, themethod comprising securing a spinal rod guide assembly to a vertebralbody, the spinal rod guide assembly comprising a spinal screw assemblyand a pair of tabs extending therefrom; positioning a spinal rod betweenthe pair of tabs; positioning a spacer having first and second ends overthe spinal rod guide assembly such that the second end of the spacerengages the spinal rod; positioning a reducer such that an outer memberof the reducer engages the first end of the spacer and an inner memberof the reducer engages at least one of the pair of tabs; moving theinner member relative to the outer member to cause a correspondingmovement of the spinal screw assembly relative to the spinal rod.

Another embodiment relates to a method of installing a spinal rod, themethod comprising providing a spinal rod guide assembly having a spinalscrew and a spinal rod holder, wherein a pair of flanges extends fromthe spinal rod holder; securing the spinal screw to a vertebral body;guiding a spinal rod between the pair of flanges to a desired positionrelative to the spinal rod holder; applying a torque to the pair offlanges about a longitudinal axis defined by the pair of flanges tobreak the pair of flanges away from the spinal rod holder; and movingthe pair of flanges away from the spinal rod holder.

Another embodiment relates to a guide assembly comprising a spinal screwassembly comprising a bone screw and a spinal rod holder, the spinal rodholder having a threaded portion; a fastener, the fastener configured tobe threadingly received by the threaded portion of the spinal rod holderand to engage a surface of a spinal rod; and a spinal rod guidecomprising upper and lower spaced apart threaded portions, the upperthreaded portion configured to threadingly receive a threaded portion ofa reduction tool, the lower threaded portion configured to threadinglyreceive the fastener; wherein the spinal rod holder is detachablycoupled to the spinal rod guide such that the threaded portion of thespinal rod holder and the lower threaded portion of the spinal rod guideenable a user to thread the fastener along both the threaded portion ofthe spinal rod holder and the lower threaded portion of the spinal rodguide in a continuous manner prior to detachment of the spinal rod guidefrom the spinal rod holder.

Another embodiment relates to a spinal rod installation kit comprising aspinal screw assembly comprising a spinal screw and a spinal rod holder,the spinal rod holder defining a threaded portion and at least oneseating surface; a fastener configured to threadingly engage thethreaded portion of the spinal rod holder to move a spinal rod towardthe at least one seating surface; a spinal rod guide comprising an upperthreaded portion and a lower threaded portion, the lower threadedportion being spaced apart from the upper threaded portion and enablingcontinuous threading of the fastener between the lower threaded portionof the spinal rod guide and the threaded portion of the spinal rodholder; and a reduction tool configured to threadingly engage the upperthreaded portion of the spinal rod guide and comprising an end portionconfigured to engage the fastener, the reduction tool enabling rotationof the fastener within the lower threaded portion of the spinal rodguide and the threaded portion of the spinal rod holder by way ofmanipulation of the reduction tool.

Another embodiment relates to a method of reducing a spinal rod, themethod comprising securing a spinal rod guide assembly to a vertebralbody, the spinal rod guide assembly comprising a spinal rod guide, aspinal rod holder coupled to the spinal rod guide, and a spinal screwextending through the spinal rod holder and into the vertebral body;positioning a spinal rod within the spinal rod guide; positioning afastener onto an end of a reduction tool and positioning the end of thereduction tool and the fastener within the spinal rod guide; rotatingthe reduction tool such that a threaded portion of the reduction toolengages and subsequently disengages an upper threaded portion of thespinal rod guide; further rotating the reduction tool such that thefastener engages a lower threaded portion of the spinal rod guide and athreaded portion of the spinal rod holder, thereby seating the spinalrod within the spinal rod holder.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features, advantages and objects of thisinvention, and the manner of attaining them, will become apparent andthe invention itself will be better understood by reference to thefollowing description of embodiments of the invention taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a side perspective view of an embodiment of a spinal rodguide/guide assembly in accordance with the principles of the presentinvention;

FIG. 2 is a side view of the spinal rod guide/guide assembly of FIG. 1;

FIG. 3 is a second side view of the spinal rod guide/guide assembly ofFIG. 1 taken from a side of the spinal rod guide/guide assembly that is90° from the side view of FIG. 2;

FIG. 4 is a sectional view of the spinal rod guide/guide assembly ofFIG. 1 taken along line 4-4 of FIG. 3;

FIG. 5 is a top plan view of the spinal rod guide/guide assembly of FIG.1 taken along line 5-5 of FIG. 3; and

FIG. 6 is a bottom plan view of the spinal rod guide/guide assembly ofFIG. 1 taken along line 6-6 of FIG. 3.

FIG. 7 is an exploded perspective view of a spinal rod guide assemblyaccording to an exemplary embodiment.

FIG. 8 is a side view of the assembly of FIG. 7 according to anexemplary embodiment.

FIG. 9 is a cross-section view of the assembly of FIG. 8 taken alongline 9-9 according to an exemplary embodiment.

FIG. 10 is a perspective view of a reduction kit according to anexemplary embodiment.

FIG. 11 is an exploded side view of the kit of FIG. 10 according to anexemplary embodiment.

FIG. 12 is a cross-sectional view of a portion of the kit of FIG. 10according to an exemplary embodiment.

FIG. 13 is a perspective view of a portion of the kit of FIG. 10 showinga reducer separated from a spacer according to an exemplary embodiment.

FIG. 14 is a cross-sectional view of the kit of FIG. 10 taken along line14-14 of FIG. 12 according to an exemplary embodiment.

FIG. 15 is a cross-sectional view of a reducer used in the kit of FIG.10 according to an exemplary embodiment.

FIG. 16 is a side view of a removal tool according to an exemplaryembodiment.

FIG. 17 is a perspective view of a guide assembly according to anexemplary embodiment

FIG. 18 is a perspective view of a portion of the guide assembly of FIG.17 according to an exemplary embodiment.

FIG. 19 is a perspective view of a portion of the guide assembly of FIG.17 according to an exemplary embodiment.

FIG. 20 is a cross sectional view of the guide assembly of FIG. 17according to an exemplary embodiment.

FIG. 21 is a perspective view of the guide assembly of FIG. 17 with aspinal rod in a first initial position and a reduction tool according toan exemplary embodiment.

FIG. 22 is a cross-sectional view of the guide assembly, spinal rod, andreduction tool of FIG. 21 according to an exemplary embodiment.

FIG. 23 is a cross-sectional view of a portion of the guide assembly andspinal rod of FIG. 21 according to an exemplary embodiment.

FIG. 24 is a cross-sectional view of a portion of the guide assembly,spinal rod, and reduction tool of FIG. 21 according to an exemplaryembodiment.

FIG. 25 is a perspective view of the guide assembly of FIG. 17 with aspinal rod in a second initial position and a reduction tool accordingto an exemplary embodiment.

FIG. 26 is a cross-sectional view of the guide assembly, spinal rod, andreduction tool of FIG. 25 according to an exemplary embodiment.

FIG. 27 is a cross-sectional view of a portion of the guide assembly andspinal rod of FIG. 25 according to an exemplary embodiment.

FIG. 28 is a cross-sectional view of a portion of the guide assembly,spinal rod, and reduction tool of FIG. 25 according to an exemplaryembodiment.

FIG. 29 is a cross-sectional view of a portion of the guide assembly,spinal rod, and reduction tool of FIG. 25 according to an exemplaryembodiment.

FIG. 30 is a cross sectional view of a portion of a guide assembly,spinal rod, and reduction tool according to an exemplary embodiment.

FIG. 31 is a cross sectional view of a portion of the guide assembly andreduction tool of FIG. 30 according to an exemplary embodiment.

FIG. 32 is a front view of a portion of a spinal guide assemblyaccording to an exemplary embodiment.

FIG. 33 is a rotated front view of a portion of a spinal guide assemblyaccording to an exemplary embodiment.

Like reference numerals indicate the same or similar parts throughoutthe several figures.

A description of the features, functions and/or configuration of thecomponents depicted in the various figures will now be presented. Itshould be appreciated that not all of the features of the components ofthe figures are necessarily described. Some of these non discussedfeatures as well as discussed features are inherent from the figures.Other non discussed features may be inherent in component geometryand/or configuration.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1-6 depict various views of a spinal rod guide/guide assemblygenerally designated 10 for the introduction, placement and securing ofa spinal rod relative to vertebrae of a patient. The spinal rod guideassembly 10 is defined by a vertebral bone screw assembly 12 that isparticularly, but not necessarily, a pedicle bone screw assembly(pedicle screw assembly) 12 and a spinal rod guide component 14. Thespinal rod guide 10 is defined by the spinal rod guide component 14. Thespinal rod guide/guide assembly 10 is made from titanium, stainlesssteel or another biocompatible material.

In one form, the spinal rod guide 10 may be considered as the spinal rodguide component 14 and, as such, the terms are interchangeable. Inanother form, the spinal rod assembly 10 may be considered as the spinalrod guide component 14 and the pedicle bone screw assembly 12 and, assuch, the terms are interchangeable.

The pedicle bone screw assembly 12 is formed of a pedicle screw 16 and aspinal rod holder or connector 18. The pedicle screw 16 is defined by athreaded body, shank or shaft 20 with a rounded head 22. A configuredsocket 24 is provided in the screw head 22. The spinal rod connector 18is situated on the pedicle screw head 22. The spinal rod connector 18and the pedicle screw head 22 are connected such that the spinal rodconnector 18 can swivel or rotate about the pedicle screw head 22. Thisallows the spinal rod connector 18 to assume various orientationsrelative to the pedicle screw 16 in order to accommodate a spinal rod(not shown).

The spinal rod connector 18 is defined by a generally tulip-shaped body26 having a lower opening 28 that is configured to allow the pediclescrew shaft 20 to extend therethrough but to retain the pedicle screwhead 22. The pedicle screw head 22 is thus sized to be rotatablycaptured by the body 26. By virtue of its shape, the body 26 has a firstside or side member 30 and a second side or side member 32 extendingfrom a base 27 of the body 26. The first and second side members 30 and32 are separated from each other on one side by a first slot 34 and onanother side by a second slot 36. The first and second side members 30and 32 are essentially situated diametrically opposite one another onthe body 26. The first and second slots 34 and 36 are likewise situateddiametrically opposite one another on the body 26 and are sized andconfigured to receive a spinal rod therein (not shown). An upper insidesurface of the first side member 30 includes threads 31, while an upperinside surface of the second side member 32 also includes threads 33.The threads 31, 32 are configured for receiving a threaded spinal rodconnector screw (not shown) for securing the spinal rod (not shown)within the spinal rod connector 18.

The spinal rod guide component 14 is defined by a first elongated arcportion or side 42 and a second elongated arc portion or side 44 thattogether defined an elongated guide tube 40. The first and secondelongated arc portions 42 and 44 are separated from one another on oneside by a first elongated slot 50 and on another side by a secondelongated slot 52. The first and second elongated arc portions 42 and 44are essentially situated diametrically opposite one another on the guidetube 40. The first and second elongated slots 50 and 52 are likewisesituated diametrically opposite one another on the guide tube 40 and aresized and configured to receive a spinal rod therein (not shown) andallow the spinal rod to slide down into the first and second slots 34and 36 of the spinal rod connector 18. In this manner, a spinal rod (notshown) is guided from an upper end 48 of the tube into the spinal rodconnector 18, and specifically into the first and second slots 34, 36 ofthe spinal rod connector 18, via the first and second elongated slots50, 52.

The guide tube 40 moreover defines a tubular bore 46 that extends fromthe upper end 48 to the spinal rod holder body 26. The tubular bore 46is sized to allow a pedicle screw driver to be received in the screwsocket 24 and for a spinal rod holder screw (not shown) to be placedinto the spinal rod connector 18 and be threadedly received by the firstand second inner threads 31, 33 of the first and second sides 30, 32 ofthe spinal rod connector body 26 in order to secure a spinal rod (notshown) therein. Other components may also be placed through the guidetube 40.

The spinal rod guide component 14 is shown having a first taper 54 on alower end of the first elongated arc portion 42 of the guide tube 40 anda second taper 56 on a lower end of the second elongated arc portion 44of the guide tube 40. It should be appreciated that such tapers are notnecessary.

In one embodiment, the spinal rod guide component 14 of the spinal rodguide assembly 10 and, more particularly, the guide tube 40 is formedwith or made to the spinal rod holder 18. Particularly, the lower end ofthe first elongated arc portion 42 of the guide tube 40 is formed withor made to the second side 32 of the spinal rod holder body 26 while thelower end of the second elongated arc portion 44 of the guide tube 40 isformed with or made to the first side 30 of the spinal rod holder body26. A first junction or juncture 55 is defined between the lower end ofthe first elongated arc portion 42 of the guide tube 40 and the secondarc portion 32 of the spinal rod holder body 26. The first juncture 55is scored or otherwise fashioned such that the first elongated arcportion 42 can break away or snap off from the second side 32. Likewise,a second junction or juncture 57 is defined between the lower end of thesecond elongated arc portion 44 of the guide tube 40 and the first side30 of the spinal rod holder body 26. The second juncture 57 is scored orotherwise fashioned such that the second elongated arc portion 44 canbreak away or snap off from the first side 30. In this manner, when thespinal rod is set and secured in the spinal rod holder 18, the spinalrod guide component 14 may be removed.

In another embodiment, the spinal rod guide 14 may be attached orattachable to a spinal rod connector 18 by threads or another means.Particularly, the lower end of the first elongated arc portion 42 of theguide tube 40 may include threads that are threadedly received bythreads on the second end 32 of the spinal rod holder body 26. Likewise,the lower end of the second elongated arc portion 44 of the guide tube40 may include threads that are threadedly received by threads on thefirst end 30 of the spinal rod holder body 26. Thus, when the spinal rodis set and secured in the spinal rod holder 18, the spinal rod guide 14may be threadedly removed from the spinal rod holder 18.

The inside surface, interior or inner lumen of the first and second arcportions (guide tube) may also include threads or threading along their(its) length. This allows a locking cap for the spinal rod holder to bethreaded down the guide tube such that the locking cap pushes the spinalrod down into the spinal rod holder along with the locking cap to securethe spinal rod into the spinal rod holder. This also provides a mannerto reduce a spondylolisthesis condition.

The present spinal rod guide/guide assembly allows easy installation ofa spinal rod into one and/or a plurality of spinal rod connectors ofpedicle screws and the fixing thereof utilizing a minimally invasivesurgical technique.

FIGS. 7-16 show a spinal rod guide/guide assembly according to variousexemplary embodiments. Referring to FIGS. 7-9, a spinal rod guideassembly 110 (e.g., a guide assembly, a spinal fixation assembly, etc.)is shown and includes a screw assembly 112 (e.g., a bone screw assemblysuch as a vertebral bone screw assembly) and a spinal rod guidecomponent 114 (e.g., a spinal rod guide, etc.). Assembly 110 is similarto spinal rod guide assembly 10 shown in FIGS. 1-6, and may include anyof the features described with respect to spinal rod guide assembly 10and FIGS. 1-6.

Spinal rod guide 114 includes a pair of arcuate members, or tabs 142,144 (e.g., flanges, extensions, arc members, etc.) that define a pair oflongitudinal slots 150, 152. Tabs 142, 144 define a generallycylindrical shaped cross-section and have a longitudinal axis 151 (seeFIG. 9). Tab 142 includes a pair of transverse slots, or recesses, 162,166. Similarly, tab 144 includes a pair of transverse slots, or recesses160, 164. The length of tabs 142, 144, the width of slots 150, 152, arethe size and position of recesses 160-166 may be varied according tovarious alternative embodiments. Referring to FIG. 8, tabs 142, 144 maybe fixedly coupled to connector 118 via one or more welds 165 (e.g.,laser welds, ultrasonic welds, resistance welds, etc.). For example,according to one embodiment, each tab 142, 144 is coupled to connector118 via three laser welds, although more or fewer welds, or differenttypes of welding techniques (e.g., resistance welding, ultrasonicwelding, etc.) may be used in alternative embodiments. As discussed ingreater detail below, welds 165 provide a rigid connection between tabs142, 144 that may later be sheared, or broken, via application of torqueto tabs 142, 144. According to other exemplary embodiments, tabs 142,144 may be coupled to connector 118 by a single continuous weld,adhesive, or a cold-formed bond. Alternatively, tabs 142, 144 may beintegrally formed with connector 118.

According to an exemplary embodiment, screw assembly 112 includes ascrew 116 (e.g., a pedicle screw) and a spinal rod holder or connector118. Connector 118 includes a body 126 and a securing member 117.Securing member 117 threadingly engages the interior of body 126 tocaptively secure screw 116 in a rotatable fashion to connector 118. Asshown in FIG. 8, body 126 may have a tulip shape, as also discussed withrespect to connector 18. For example, body 126 may include a bulgeportion 119 (see FIG. 8) that has a diameter greater than the diameterof the top and/or bottom of body 126. In some embodiments, a portion ofconnector 118 (e.g., bulge portion 119) has a diameter greater than thediameter defined by tabs 142, 144 (e.g., a cylinder encompassing tabs142, 144). This may minimize the required skin incision and reducemuscle trauma relative to more invasive systems. Also, the tulip-shapedbody is configured to allow a greater degree of freedom for theinsertion angle and orientation of connector 118. As shown in FIG. 9,connector 118 is configured to receive a spinal rod 121. Spinal rod 121may be made of any appropriate material, and have any diameter andlength to suit a particular application.

As also discussed with respect to FIGS. 1-6, screw 116 is configured tobe secured to a bone (e.g., a vertebral body) of a patient. Screw 116 iscaptively held by connector 118. Connector 118 is in turn configured toreceive spinal rod 121, which is secured to connector 118 via a fastener(not shown). Spinal rod 121 may be guided into position using spinal rodguide 114, such that spinal rod 121 may be slid down within slots 150,152 and between tabs 142, 144. Once in position, the fastener (notshown) is tightened to secure spinal rod 121 in place within connector118.

In some situations, various factors (spinal irregularities,spondylolisthesis, etc.) may prevent the proper “seating” of spinal rod121 within connector 118. In other words, in some cases spinal rod 121may not be positionable adjacent to surface 115 (see FIG. 7) ofconnector 118, and will instead be positioned at some distance (e.g., 1mm, 5 mm, etc.) from surface 115 and a “fully seated” position. In suchinstances, it may be necessary to “reduce” the spinal rod to the fullyseated position, as discussed in greater detail below.

Referring now to FIGS. 10-16, various components and methods forreducing a spinal rod are showing according to various exemplaryembodiments. As shown in FIG. 11, a kit 169 for reducing a spinal rod isshown according to en exemplary embodiment, and includes a guideassembly 110, a spacer 190, and a reducer 170. As discussed in detailherein, kit 169 is usable to fully reduce a spinal rod such as spinalrod 121 to a fully seated position. In some embodiments, kit 169 isconfigured to reduce spinal rod 121 a maximum of 20 mm. According tovarious other embodiments, kit 169 may be configured to providereduction of greater or lesser amounts.

Referring to FIGS. 10-13, spacer 190 (e.g., a counter-torque wrench ormember, etc.) is a generally cylindrical member having a hollow,cylindrical body 192, a first end 194, and a second end 196. End 196includes a pair of notches or recesses 198 configured to receive spinalrod 121 and prevent rotation of spinal rod 121 relative to spacer 190.End 194 may include a hexagonal or other shaped portion configured toprevent relative rotation between spacer 190 and one or more portions ofreducer 170.

According to an exemplary embodiment, reducer 170 includes a pair ofouter members shown as a knob 172 and a sleeve 174, and an inner membershown as shaft 176. Reducer 170 is configured to engage spacer 190 andguide assembly 110 such that reducer 170 enables a user to reduce spinalrod 121 relative to guide assembly 110.

Referring to FIGS. 11 and 15, knob 172 is threadingly coupled to shaft176 such that rotation of knob 172 causes a corresponding movement(e.g., longitudinal or translational movement) of shaft 176 relative toknob 172. Knob 172 may take any appropriate shape and/or size and bemade of any appropriate material.

Sleeve 174 is slidably positioned on shaft 176. According to oneembodiment, sleeve 174 is configured such that shaft 176 may freelyslide longitudinally within sleeve 174, but shaft 176 may not rotaterelative to sleeve 174. For example, a pin or other extension may extendfrom the exterior of shaft 176 and be received within a longitudinallypositioned slot on sleeve 174 such that longitudinal, but notrotational, relative movement is permitted between sleeve 174 and shaft176. Thus, as knob 172 is rotated, shaft 176 moves, or translates, in alongitudinal manner relative to sleeve 174.

According to one embodiment, shaft 176 of reducer 170 includes a pair ofextensions 178, with each extension 178 including a tab 180. Extensions178 are formed in an arcuate fashion such that the curvature ofextensions 178 and tabs 180 generally matches the curvature of tabs 142,144. Furthermore, the outside diameter of extensions 178 is configuredto provide a snug, but sliding fit of extensions 178 within the interiorof spacer 190 (which may have a cylindrically-shaped interior).Furthermore, in order to prevent inward deflection of extensions 178and/or tabs 142, 144, a cylindrical guide rod 171 (e.g., a switchingstick) may be introduced within tabs 142, 144 (see FIG. 10). Asdiscussed in greater detail below, this may facilitate maintaining aproper interface between extensions 178/tabs 180 and tabs 142, 144.

In order to reduce spinal rod 121, spacer 190 is slid over guideassembly 110 such that notches 198 receive spinal rod 121. If desired,center guide or switching stick 171 may be introduced within tabs 142,144. Reducer 170 is positioned such that extensions 178 slide betweentabs 142, 144 (e.g., within longitudinal slots 150, 152) untilextensions 178 may be rotated such that tabs 180 are received withinrecesses 160, 162 in tabs 142, 144. According to one embodiment, tabs180 and recesses 160, 162 have complimentary shapes such thatlongitudinal movement of extensions 178 and tabs 180 causes acorresponding longitudinal movement of tabs 142, 144, and in turn,connector 118. In other embodiments, tabs 180 and recesses 160, 162 mayprovide a bayonet-type connection. When reducer 170 is positioned, end182 of sleeve 174 engages end 194 of spacer 190 so as to preventrelative longitudinal or rotational movement between sleeve 174 andspacer 190. Furthermore, according to one embodiment, sleeve 174 andshaft 176 may be keyed to one another so as to permit longitudinal, butnot rotational, movement between the components.

With reducer 170 and spacer 190 in proper position, knob 172 of reducer170 may be rotated (e.g., in a clockwise fashion) upon shaft 176,causing shaft 176 to move upward (e.g., away from a patient's body)through knob 172 and sleeve 174, thereby pulling spinal rod guideassembly 110 upward in a corresponding manner due to the engagement oftabs 180 with recesses 160, 162. Thus, as knob 172 is rotated, thedistance between connector 118 and line A shown in FIG. 10 is decreased(in effect, pulling the bone screw and the vertebral body toward theuser/physician). At the same time, spacer 190, due to its engagement atend 194 with sleeve 174 and its engagement at end 196 with spinal rod121, maintains a constant distance between spinal rod 121 and line Ashown in FIG. 10. In other words, as knob 172 is rotated, shaft 176 andtabs 142, 144 move upward within spacer 190, thereby moving connector118 toward spinal rod 121, which is held in place by spacer 190. Uponfurther rotation of knob 172, connector 118 will eventually be moved asufficient distance relative to spinal rod 121 such that spinal rod 121is in a fully seated position and may be fastened into place.

Providing a reduction kit such as kit 169 provides advantages over moreconventional reduction techniques. For example, tabs 142, 144 serve thedual purposes of guiding spinal rod 121 into position, and enabling auser to reduce spinal rod 121 if necessary, thereby reducing the numberof tools, fixtures, etc., required for a spinal fixation procedure.Furthermore, because the reduction components are all contained withinspacer 190, the procedure is minimally invasive and does not requireadditional access space, etc., in order to reduce the spinal rod.

Referring now to FIG. 16, a removal tool 200 is shown according to anexemplary embodiment. As shown in FIG. 16, tool 200 includes a handle202, a generally cylindrical shaft 204 extending from handle 202, and anumber of pins, or extensions, 206, 208, extending from shaft 204.According to one embodiment, extensions 206, 208 are sized and locatedsuch that when tool 200 is inserted into guide assembly 110, extensions206, 208 may be received within recesses 160-166. As such, rotation oftool 200 will generate a corresponding torque on tabs 142, 144. In someembodiments, recesses 160-166 may be provided at an angle other than 90degrees relative to the length of tabs 142, 144 such that as tool 200 isrotated, the tool tends move “upward” along the recesses. As such, botha rotational and longitudinal force may be applied to the tabs. Uponapplication of sufficient torque/force, tabs 142, 144 are configured toseparate (e.g., break away, shear from, etc.), connector 118, such thattabs 142, 144 may be removed from a procedural area. While in someembodiments tabs 142, 144 are removed by applying a torque via tool 200,according to other embodiments, other methods of removing tabs 142, 144may be used, including pulling tabs 142, 144 straight off (e.g., alongthe longitudinal axis of the tabs), bending the tabs inward/outward,etc. In some embodiments, tabs 142, 144 are moved in a non-bendingmanner during removal (e.g., via rotational about their longitudinalaxis, via puling along their longitudinal axis, a combination thereof,etc.).

Tool 200 and guide assembly 110 provide an easy and minimally invasivemeans for removing tabs 142, 144 from connector 118. In contrast toother techniques, which may require bending, rocking, or othermanipulation of various components against the surrounding muscle, bone,tissue, etc., tool 200 is configured to be received within tabs 142,144, such that in one embodiment rotation of tool 200 is the onlyforce/torque required to break away tabs 142, 144 from connector 118.Furthermore, no additional tools, etc. are required to break away andremove tabs 142, 144.

The systems and methods described herein provide may provide manybenefits over more traditional means of installing and reducing spinalrods and similar components. For example, tabs 142, 144 act as rigidfenestra without the concern of the tabs falling off during a procedure,due to the rigid, laser-welded connection of the tabs to the spinal rodholder. Further, the components provide a minimally invasive techniquethat minimizes the trauma to the patient and the length of the procedure(e.g., as a result of the easy removal feature of the tabs, etc.).

Referring now to FIGS. 17-33, various components and methods forreducing a spinal rod are showing according to various exemplaryembodiments. Referring to FIGS. 17-20, a spinal rod guide assembly 310(e.g., a guide assembly, a spinal fixation assembly, etc.) is shown andincludes a screw assembly 312 (e.g., a bone screw assembly such as avertebral bone screw assembly, etc.) and a spinal rod guide component314 (e.g., a spinal rod guide, etc.). Assembly 310 may share certainfeatures with spinal rod guide assemblies 10 and 110, and may includeany of the features discussed in connection therewith.

Spinal rod guide 314 includes a pair of arcuate members, or tabs 342,344 (e.g., flanges, extensions, arc members, etc.) that define a pair oflongitudinal slots 350, 352 and a central bore 353. Tabs 342, 344 definea generally cylindrical shaped cross-section and have a longitudinalaxis 351 (see FIG. 17). Tab 342 includes a pair of transverse slots, orrecesses 360, 362. Similarly, tab 344 includes a pair of transverseslots, or recesses 360, 362. The length of tabs 342, 344, the width ofslots 350, 352, and the size and position of recesses 360, 362 may bevaried according to various alternative embodiments.

Referring to FIGS. 18 and 19, tabs 342, 344 terminate at an upper end ata top 370 and terminate at a lower end at a spinal rod holder 318. Tabs342, 344 may be detachably coupled to spinal rod holder 318 via one ormore joints shown as welds 363 (e.g., laser welds, ultrasonic welds,resistance welds, etc.). For example, according to one embodiment, eachtab 342, 344 is coupled to spinal rod holder 318 via one continuousweld, although more welds, or different types of welding techniques(e.g., resistance welding, ultrasonic welding, etc.) may be used inalternative embodiments. As discussed in greater detail below, welds 363provide a rigid connection between tabs 342, 344, and spinal rod holder318. According to other exemplary embodiments, tabs 342, 344 may becoupled to spinal rod holder 318 via three laser welds that may later besheared, or broken, via application of torque to tabs 342, 344, althoughmore or fewer welds, or different types of joining techniques (e.g.,resistance welding, ultrasonic welding, adhesives, or a cold-formedbond, etc.) may be used in alternative embodiments. Alternatively, tabs342, 344 may be integrally formed with spinal rod holder 318.

According to one embodiment, spinal rod holder 318 includes a pair ofupstanding portion 367, 369 that extend upward and are coupled to tabs342, 344 by welds 363. Each of upstanding portions 367, 369 includes afracture joint, or joint 365 that defines a plurality of struts 390 (seeFIGS. 32-33) extending between intermediate threaded portion 376 andlower threaded portion 380 along longitudinal axis 351. For example, asshown in FIGS. 32-33, each tab 342, 344 may be joined to upstandingportions 367, 369 by way of three spaced apart struts 390, with grooves,or recesses 388 being located between adjacent struts. Grooves 388 maybe machined grooves. In other embodiments, more or fewer struts may beutilized, and the shape and/or size of the struts may be varied to suita particular application. Grooves 338 and struts 390 are configured toprovide the desired strength and fracture properties between spinal rodguide 314 and the portion of spinal rod holder 318 above joint 365 fromthe remainder of spinal rod holder 318. The size and number of struts390 enable the amount of torque required to detach spinal rod guideassembly 314 from spinal screw assembly 312 to be controlled.Additionally, the design of the struts and grooves provides greatercolumn support/strength for tabs 342, 344 relative to other couplingmethods while maintaining a consistent removal/fracture torque.

Top 370 is a generally cylindrical and/or polygonal member, or ring,that extends between tabs 342, 344 in a fully closed fashion to join theends thereof. Top 370 defines an upper threaded portion 372 of spinalrod guide 314 which, as discussed in greater detail below, is configuredto engage a threaded portion 384 of a reduction tool 382 (see FIG. 22).The opposite ends of tabs 342, 344 terminate at weld 363 above anintermediate threaded portion 376 of spinal rod guide 318. In oneembodiment, upper threaded portion 372 has a larger thread pitch thanintermediate threaded portion 376 to provide different types ofadjustment (e.g., coarse vs. fine) depending on which threads are used.For example, for initial reduction, coarser threads may be used toprovide a faster reduction, while for final reduction adjustments, finerthreads may be desirable to enable finer adjustments.

According to an exemplary embodiment, screw assembly 312 includes ascrew 316 (e.g., a pedicle screw, etc.) and spinal rod holder or spinalrod holder 318. Spinal rod holder 318 includes a body 326, upstandingportions 367, 369, and a securing member 329. Securing member 329captively secures screw 316 in a rotatable fashion to spinal rod holder318. As shown in FIG. 32, body 326 may have a tulip shape, as alsodiscussed with respect to spinal rod holder 18. For example, body 326may include a bulge portion 319 (see FIG. 32) that has a diametergreater than the diameter of the top and/or bottom of body 326. In someembodiments, a portion of spinal rod holder 318 (e.g., bulge portion319) has a diameter greater than the diameter defined by tabs 342, 344(e.g., a cylinder encompassing tabs 342, 344). This may minimize therequired skin incision and reduce muscle trauma relative to moreinvasive systems. Also, the tulip-shaped body is configured to allow agreater degree of freedom for the insertion angle and orientation ofspinal rod holder 318. One or more flat portions 389 (see, e.g., FIGS.32-33) may be formed on spinal rod holder 318 and be usable, forexample, as a gripping and/or engagement surface for one or more tools,etc. As shown in FIG. 29, spinal rod holder 318 is configured to receivea spinal rod 321. Spinal rod 321 may be made of any appropriatematerial, and have any diameter and length to suit a particularapplication.

As shown in FIG. 20, intermediate threaded portion 376 and lowerthreaded portion 378 of spinal rod holder 318 form a nearly continuousthreaded portion having a substantially constant thread pitch, such thata fastener such as fastener 317 can be continuously threaded alongintermediate threaded portion 376 and lower threaded portion 380 ofspinal rod holder 318. As discussed above, spinal rod guide assembly 310includes three separate threaded portions, including upper threadedportion 372 of spinal rod guide 314, intermediate threaded portion 376of spinal rod holder 318, and lower threaded portion 380 of spinal rodholder 318.

Screw 316 is configured to be secured to a bone (e.g., a vertebral body,etc.) of a patient. Screw 316 is captively held by spinal rod holder318. Spinal rod holder 318 is in turn configured to receive spinal rod321, which is secured to spinal rod holder 318 via fastener 317 (e.g., alocking collar, screw, etc.). Spinal rod 321 may be guided into positionusing spinal rod guide 314, such that spinal rod 321 may be slid downwithin slots 350, 352 and between tabs 342, 344. Once in position,fastener 317 is tightened to secure spinal rod 321 in place withinspinal rod holder 318.

In some situations, various factors (e.g., spinal irregularities,spondylolisthesis, etc.) may prevent the proper “seating” of spinal rod321 within spinal rod holder 118. In other words, in some cases spinalrod 321 may not be positionable adjacent to a seating surface 315 (seeFIG. 19) of connector 318, and will instead be positioned at somedistance (e.g., 1 mm, 5 mm, etc.) from surface 315 and a “fully seated”position. In such instances, it may be necessary to “reduce” the spinalrod to the fully seated position, as discussed in greater detail below.

Referring now to FIGS. 21-31, various components and methods forreducing a spinal rod (e.g., to restore one or more vertebral bodies orother parts to a substantially normal anatomical position, etc.) areshown according to various exemplary embodiments. As shown in FIGS.21-22, a tool 382 usable to reduce a spinal rod such as spinal rod 321may be a generally elongated, cylindrical member that tapers along allor a portion of its length (e.g., to facilitate insertion and/or removalof the tool). Tool 382 includes a threaded portion 384 spaced apart froman end portion 386. Threaded portion 384 is configured to threadinglyengage upper threaded portion 372 of spinal rod guide 314, and endportion 386 is configured to engage fastener 317 in a rotationally fixedfashion (e.g., by way of correspondingly shaped hex-heads/sockets, etc.)such that rotation of tool 382 causes a corresponding rotation offastener 317.

According to an exemplary embodiment, tool 382 and assembly 310 areconfigured such that threaded portion 384 is threadingly received byupper threaded portion 372. Threaded portion 384 is spaced apart fromend 386 such that threaded portion 384 disengages from upper threadedportion 372 prior to fastener 317 engaging intermediate threaded portion376. The spacing between the various threaded portions and the length oftool 382 may be varied to suit a particular application. Thisconfiguration allows a user to reduce a spinal rod a first amountthrough the engagement of tool 382 and upper threaded portion 372, andto reduce the spinal rod a second amount through the engagement offastener 317 and intermediate threaded portion 376 and lower threadedportion 380. Upper threaded portion 372 and intermediate threadedportion 376 provide supplemental reduction capabilities in addition tothe reduction enabled by lower threaded portion 380.

In use, spinal screw 316 is fastened to a vertebral body, and spinal rod321 is slid into an initial position as discussed above. Referring toFIGS. 21-24, the initial position of spinal rod 321 may be such thatfastener 317 is above, or outside of, intermediate threaded portion 376of spinal rod holder 318. As such, threaded portion 384 of tool 382 maybe threaded into upper threaded portion 372 of spinal rod guide 314. Astool 382 is rotated, tool 382 (and, therefore, fastener 317) movesrelative to spinal rod guide 314 such that fastener 317 pushes spinalrod 321 toward intermediate threaded portion 376. Upper threaded portion372, in combination with the instrumentation of tool 382 and threadedportion 384, provides a greater amount of reduction of the spinal rodrelative to more traditional techniques.

Referring to FIGS. 30-31, just prior to fastener 317 engagingintermediate threaded portion 376 (see FIG. 30), threaded portion 384 oftool 382 disengages upper threaded portion 372 (see FIG. 31). Thisdisengagement/engagement feature prevents simultaneous threading on bothupper threaded portion 372 and intermediate threaded portion 376.Fastener 317 may then be threadingly moved within intermediate threadedportion 376 and lower threaded portion 380 to further reduce spinal rod321 toward a seated position (e.g., proximate seating surface 315), asdiscussed in greater detail below.

Referring now to FIGS. 25-29, in some instances, the initial position ofspinal rod 321 may be such that fastener 317 is within (or immediatelyadjacent) intermediate threaded portion 376 of spinal rod holder 318(see, e.g., FIGS. 27-28) upon engaging spinal rod 321. In such cases,tool 382 is first threaded through upper threaded portion 372, and end386 of tool 382 is used to engage fastener 317 with intermediatethreaded portion 376 (see FIG. 28). Tool 382 may be rotated to therebymove fastener 317 and spinal rod 321 along intermediate threaded portion376 and lower threaded portion 380 to a fully seated position (see FIG.29), where spinal rod 321 is proximate seating surface 315. Intermediatethreaded portion 376 and lower threaded portion 380 provided an extendedlength of threads for spinal rod holder 318, thereby providing a greateramount of rod reduction relative to more traditional systems.

Once spinal rod 321 is properly seated and secured by fastener 317, anappropriate tool may be used to detach spinal rod guide 314 andintermediate threaded portion 376 from the remainder spinal rod holder318. In some embodiments, a generally cylindrical, elongated tool havingone or more projections is used such that the projections on the toolengage recesses 360, 362 on spinal rod guide 314 and permit a user toapply a torque to tabs 342, 344. Upon application of sufficient torque,fracture joint 365 fractures (break, etc.), enabling a user to removethe tool with spinal rod guide 314 and intermediate threaded portion376. In various alternative embodiments, other means for removing spinalrod guide 314 and intermediate threaded portion 376 may be utilized.

In some embodiments, the tooling and spinal guide assembly disclosedherein may be configured to reduce a spinal rod a maximum of 20 mm.According to various other embodiments, the components may be configuredto provide reduction of a spinal rod of greater or lesser amounts. Allsuch applications are to be understood to be within the scope of thepresent disclosure.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly exemplary embodiments have been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A guide assembly comprising: a reduction tool; aspinal rod guide comprising an upper threaded portion, the upperthreaded portion configured to threadingly receive a threaded portion ofthe reduction tool; a spinal screw assembly comprising a bone screw anda spinal rod holder, the spinal rod holder comprising an intermediatethreaded portion and a lower threaded portion; a fastener, the fastenerconfigured to be threadingly received by the intermediate and lowerthreaded portions and to engage a surface of a spinal rod; wherein thespinal rod guide and the intermediate threaded portion are detachablycoupled to the remainder of the spinal rod holder such that theintermediate and lower threaded portions of the spinal rod holder enablea user to thread the fastener along both the intermediate threadedportion and the lower threaded portion of the spinal rod holder in acontinuous manner prior to detachment of the spinal rod guide and theintermediate threaded portion from the remainder of the spinal rodholder; and wherein an end of the reduction tool is configured to engagethe fastener such that the threaded portion of the reduction tooldisengages the upper threaded portion of the spinal rod guide prior tothe fastener engaging the intermediate threaded portion of the spinalrod holder.
 2. The guide assembly of claim 1, wherein the spinal rodguide comprises first and second arc portions defining first and secondslots extending along a longitudinal axis of the spinal rod guide,wherein the first and second arc portions are configured to break awaywith the intermediate threaded portion at a fracture joint upon apredetermined amount of torque being applied to the first and second arcportions about the longitudinal axis.
 3. The guide assembly of claim 2,wherein each of the first and second arc portions are coupled to thespinal rod holder by a welded joint between each of the first and secondarc portions and the spinal rod holder.
 4. The guide assembly of claim2, wherein the fracture joint comprises a plurality of struts beingprovided on surface of the spinal rod holder.
 5. The guide assembly ofclaim 2, wherein the spinal rod guide comprises a ring member joiningthe first and second arc portions and defining at least a portion of theupper threaded portion.
 6. The guide assembly of claim 1, wherein thespinal rod guide comprises first and second arc portions comprisinginternal surfaces defining a recess configured to receive the threadedportion of the reduction tool after the threaded portion of thereduction tool disengages the upper threaded portion of the spinal rodguide, thereby enabling longitudinal movement of the threaded portion ofthe reduction tool within the recess as the fastener engages theintermediate threaded portion of the spinal rod holder.
 7. The guideassembly of claim 6, wherein the upper threaded portion of the spinalrod guide has a greater thread pitch than the intermediate threadedportion of the spinal rod holder, and wherein the intermediate threadedportion of the spinal rod holder has substantially the same thread pitchas the lower threaded portion of the spinal rod holder.
 8. The guideassembly of claim 1, wherein the spinal rod guide comprises first andsecond arc portions extending from a pair of seating surfaces of thespinal rod holder, and wherein the fastener is configured to enable auser to thread the fastener along the intermediate and lower threadedportions to secure the spinal rod proximate the seating surfaces of thespinal rod holder.
 9. A spinal rod installation kit comprising: a spinalrod guide comprising an upper threaded portion; a spinal screw assemblycomprising a spinal screw and a spinal rod holder, the spinal rod holderdefining an intermediate threaded portion, a lower threaded portion, andat least one seating surface; a fastener configured to threadinglyengage the intermediate and lower threaded portions of the spinal rodholder to move a spinal rod toward the at least one seating surface; areduction tool configured to threadingly engage the upper threadedportion of the spinal rod guide and comprising an end portion configuredto engage the fastener, the reduction tool enabling continuous threadingof the fastener within the intermediate threaded portion of the spinalrod holder and the lower threaded portion of the spinal rod holder byway of manipulation of the reduction tool; and wherein the reductiontool disengages the upper threaded portion prior to the fastenerengaging the intermediate threaded portion.
 10. The kit of claim 9,wherein the spinal rod guide comprises an internal recess configured toenable longitudinal movement of a threaded portion of the reduction toolas the fastener engages the intermediate threaded portion.
 11. The kitof claim 9, wherein the spinal rod guide comprises a pair of arcportions extending from a ring portion at a first end and extending fromthe spinal rod holder at a second end.
 12. The kit of claim 11, whereineach of the pair of arc portions is coupled to the spinal rod holder viaa welded joint.
 13. The kit of claim 12, wherein a plurality of strutsextends longitudinally along the spinal rod holder between theintermediate and lower threaded portions to define a fracture joint, andwherein adjacent struts are divided by notches.
 14. The kit of claim 12,wherein the fracture joint is configured to break upon application of apredetermined amount of torque.
 15. A method of reducing a spinal rod,the method comprising: securing a spinal rod guide assembly to avertebral body, the spinal rod guide assembly comprising a spinal rodguide, a spinal rod holder coupled to the spinal rod guide, and a spinalscrew extending through the spinal rod holder and into the vertebralbody; positioning a spinal rod within the spinal rod guide; positioninga fastener onto an end of a reduction tool and positioning the end ofthe reduction tool and the fastener within the spinal rod guide;rotating the reduction tool such that a threaded portion of thereduction tool engages and subsequently disengages an upper threadedportion of the spinal rod guide; further rotating the reduction toolsuch that, after the threaded portion of the reduction tool disengagesthe upper threaded portion of the spinal rod guide, the fastener engagesan intermediate threaded portion of the spinal rod holder and a lowerthreaded portion of the spinal rod holder in a continuous threadingmanner, thereby seating the spinal rod within the spinal rod holder. 16.The method of claim 15, wherein the spinal rod guide comprises a pair ofarc portions extending from a circumferentially closed top to the spinalrod holder.
 17. The method of claim 15, wherein the spinal rod holdercomprises at least one fracture joint comprising a plurality of strutsprovided between the intermediate and lower threaded portions.
 18. Themethod of claim 15, further comprising applying a torque to the spinalrod guide to fracture the struts.